Comparative transcriptome analysis revealed differential gene expression involved in wheat leaf senescence between stay-green and non-stay-green cultivars

Abstract

Breeders agree that leaf senescence is a favorable process for wheat seed yield improvement due to the remobilization of leaf nutrients. However, several studies have suggested that staying green may be an important strategy for further increasing wheat yields. In this study, we performed a comparative transcriptome analysis between wheat cultivars CN17 and CN19 after heading and also measured photosynthetic parameters, chlorophyll (Chl) contents, and antioxidant enzyme activities at various time points after heading. The physiological and biochemical indexes revealed that CN17 exhibited a functionally stay-green phenotype while CN19 did not. We identified a total of 24,585 and 34,410 differential expression genes between genotypes at two time-points and between time-points in two genotypes, respectively, and we also found that 3 (37.5%) genes for leaf senescence, 46 (100%) for photosynthesis – antenna protein, 33 (70.21%) for Chl metabolism and 34 (68%) for antioxidative enzyme activity were upregulated in CN17 compared with CN19 during leaf senescence, which could be regulated by the differential expression of SAG39 (senescence-associated gene 39), while 22 (100%) genes for photosynthesis – antenna proteins, 6 (46.15%) for Chl metabolism and 12 (80%) for antioxidative enzyme activity were upregulated in CN17 compared with CN19 before the onset of leaf senescence. Here, we further clarified the expression profiles of genes associated with a functional stay-green phenotype. This information provides new insight into the mechanism underlying delayed leaf senescence and a new strategy for breeders to improve wheat yields.

Leaf Senescence Regulation Mechanism Based on Comparative Transcriptome Analysis in Foxtail Millet

“…H 2 O 2 and MDA levels were found to be lower in LS compared to SS during DIS, which could be explained by the increased activities of antioxidant enzymes (SOD and CAT) in LS (Figure 2). These results suggest that the activation of the enzymatic ROS scavenging system in LS reduced ROS accumulation and delayed its dark-induced leaf senescence, which was supported by previous studies in other plant species [26,36]. Flavonoids were previously reported to possess the capacity to scavenge ROS and mitigate oxidative damage in plants [37].…”

“…It has been reported that the promoter of SAG39 is implicated in the negative regulation of leaf senescence in rice [48]. A comparative transcriptome analysis further revealed that TaSAG39 delayed the senescence process by maintaining the stability of chlorophyllprotein complexes in a stay-green wheat cultivar [26]. Our research also indicated that the senescence-delaying foxtail millet LS maintained a higher chlorophyll content during the DIS (Figure 1B).…”

“…Transcriptomic analyses have identified a large number of the underlying SAGs and TFs in crops, including maize, sorghum, wheat, and rice, which provide valuable insights into the regulation of leaf senescence [24][25][26][27]. Dark treatment is a stable and controlled carbon-starvation-induced senescence system, extensively employed for the characteri-zation and analysis of various senescence phenotypes [28,29].…”

Using UAV-Based Temporal Spectral Indices to Dissect Changes in the Stay-Green Trait in Wheat

“…Previous studies on the genetics of SG traits in wheat have primarily focused on identifying QTL [ 8 , 10 , 49 ]. In this study, by combining genetic analysis, we observed that the SG candidate genes identified here had signs of selection in past wheat breeding.…”

A multiscale approach to investigate fluorescence and NDVI imaging as proxy of photosynthetic traits in wheat

“…According to Thomas and Ougham (2014), breeders tend to avoid using cosmetic stay-greens because they do not offer any yield benefits. The opposite type, functional stay-green, is more desirable for breeding purposes as photosynthesis is maintained longer during the maturation phase (Thomas & Ougham, 2014; Li et al ., 2022). However, screening populations for functional stray-green genotypes is complicated as it would require gas-exchange measurements at multiple time points on a large number of individuals, which is not feasible without a large number of instruments and trained users.…”